The long term objective of this proposal is to identify the mechanisms and factors which regulate expression of the human papillomavirus types associated with anogenital malignancies. HPV types 16, 18, 31, 33 and 51 specifically infect the anogenital area and are etiological agents of cervical and other genital cancers. The life cycle of human papillomaviruses is closely linked to epithelial differentiation with viral amplification and virion production being restricted to suprabasal cells. In this application, I propose to examine the factors that regulate both differentiation-induced and constitutive HPV expression. The primary positive activator of HPV expression is an enhancer located in the Upstream Regulatory Region (URR) referred to as the constitutive or C enhancer. This enhancer is dependent solely on cellular factors for function and is active in all cells of the epithelium. For HPV-18, a keratinocyte-specific factor called KRF-1 together with AP-1 are required for C enhancer function. Additional HPV promoters and enhancers are activated upon differentiation of infected cells. These include a promoter for E1^E4 expression which has been localized to the E7 ORF as well as the late promoter. We propose to use our ability to duplicate most aspects of a productive HPV infection in raft cultures to examine the regulation of viral expression as a function of differentiation. Specifically I propose to: (1) clone and characterize the keratinocyte specific KRF-l factor which activates C enhancer function of HPV-18, (2) identify and characterize the factors that regulate constitutive HPV 31b expression in basal cells and neoplasias, (3) examine the mechanisms by which expression ofHPV-31b promoters are activated by differentiation in vitro, (4) examine the role of E2 molecules in regulating HPV-31b expression in stratifying epithelial cells.